I was under the impression that to get an S-Rank on any given "section" you'd have to make sure nothing was missed, and that you never got hit. However, in this video (around 9:55, a bit after the time the link should drop you in), the player hits the wall and takes damage — at the end, though, they still get an S-Rank, both in that "section" (even though "no damage" isn't there) and in the level as a whole.

Am I missing something about how to get an S-Rank? Is it more about points, and less about missing or not missing thumps, and taking damage?